A simplified method for steady state and transient state thermal analysis of hybrid steel and FRP RC beams at fire

Abstract

This paper suggests and validates a simplified analytical method for thermal steady state and transient state analysis of hybrid steel and FRP reinforced concrete beams exposed to elevated temperature induced by fire. The proposed method predicts the flexural resistance of concrete beams based on strain compatibility and force equilibrium of the beam section under pure bending moment taking into account the deterioration in mechanical properties of concrete, steel and FRP bars due to the rise of temperature. The accuracy of the suggested method was ascertained against the corresponding experimental tests results. Validation results, in terms of load-displacement curves; displacement- time histories and failure modes, have shown the reliability and feasibility of the suggested analytical method. Afterward, the verified method was implemented in investigating the effect of important parameters on the response and failure of hybrid steel and FRP reinforced concrete beams under elevated temperature such as concrete cover, reinforcement ratio, and heating rate. The results extracted from the parametric study have come up with interesting conclusions which may be utilized in the design of thermally exposed concrete beams with hybrid reinforcement.